Economics research paper: Human fertilizer and the productivity of farming households

I’m not quite sure if this is the best place to post this or if it should be somewhere else. Anyway, my name is Johan Wikström and I have together with my colleague Jan Pettersson performed a research project on the use of ecological sanitation and the reuse of human fertilizer in rural Mali, West Africa. We did it at the Economics department at Uppsala University in Sweden. The study aimed to measure if households having UDDT’s installed and therefore access to human fertilizer had higher yields of farming than equivalent households without UDDT’s. Or if they substituted artificial fertilizer with human fertilizer. Our research paper, named Human fertilizer and the productivity of farming households, has now been published in the journal Agroecology and Sustainable Food Systems.

To our knowledge there hasn’t been much research performed at all in this field, measuring the actual use/reuse in the real world and what impact the use/reuse has on farming yields. If anyone knows of studies that have measured the actual real world effect on yield levels or substitution effects on artificial fertilizer, please let me know.

We got significant results showing a somewhat higher yield of farming on maize fields for households with UDDT’s than the control households.

We also found that the households with UDDT’s substituted artificial fertilizer with human fertilizer, which we believe is bad strategy since more fertilizer is needed and not less.

An interesting behavioral finding of our study was that only a small fraction of the potential amount of feces and urine was reused. We haven’t discussed why that is the case but it is of course of very important question.

Please see the abstract below for more information and our main findings and further down the link to the paper.

ABSTRACT
Ecological sanitation offers both sanitation and fertilizer
through recycling of nutrients. Human fertilizer provides a
close to free addition of nutrients in household farming and
may, therefore, decrease the downward risk of fertilizer adoption.
We study an ecological sanitation investment program in
southern Mali, where just over 150 beneficiaries got a urine
diverting dry toilet installed. Our results suggest that the average
household in our study is able to produce amounts of N, P,
and K equivalent to around a fourth of its yearly expenditures
on artificial fertilizers, corresponding to a yearly addition of
nutrients or a yearly reduction in fertilizer expenditures to a
value of about 50 €. However, the quantity and quality of N, P,
and K actually retained is found to be only a fraction of this
potential amount. Using propensity score matching methods,
we find an increase in maize yields among beneficiary households,
but no effect on the yields of other crops. Moreover,
households substitute artificial fertilizer with human fertilizer at
10–15% of the average household use of artificial fertilizers.
Thus, the substitution may worsen an already bad soil nutrient
balance. Higher retention levels are needed for solutions to
prove financially viable.

Re: Economics research paper: Human fertilizer and the productivity of farming households

Thanks for posting here. That's really interesting that you did this research at the economics department!

The link that you posted leads to a journal paper behind a paywall. Could you provide other links or files that are accessible for free (had you considered making your paper open access? Please do in future). E.g. past conference presentations?

Who installed those UDDTs in Mali?

Also you said:

Our results suggest that the average household in our study is able to produce amounts of N, P, and K equivalent to around a fourth of its yearly expenditures on artificial fertilizers, corresponding to a yearly addition of nutrients or a yearly reduction in fertilizer expenditures to a value of about 50 €

How does 50 Eur per year compare to other expenditures - is it regarded as a lot or not a lot?

And you said:

An interesting behavioral finding of our study was that only a small fraction of the potential amount of feces and urine was reused. We haven’t discussed why that is the case but it is of course of very important question.

What are your theories why this is the case? It is because it is too much "hassle" to apply it? Or because the fertiliser from the UDDTs is not available at the right time of the year in the right quantity?

Which aspects of your research were of particular relevance to the people in the economics department that you worked with?

Re: Economics research paper: Human fertilizer and the productivity of farming households

Hej Johan,
Nice to see that you did this work in Mali and with interesting findings.
I came across another study that was done in Mali too, though only focusing on the use of urine. It also included an overview of urine fertilizer promotion projects done by PeaceCorps in several Malian towns.
A link to the pdf is here:
www.mtu.edu/peacecorps/programs/civil/pd...haw-thesis-final.pdf

Re: Economics research paper: Human fertilizer and the productivity of farming households

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Please find the article attached.

50 euro is a lot for a subsistence farmer in Mali. But since the soils are very poor in nutrients it would be beneficial to add another 50 euros worth of reuse fertilizer than to decrease the artificial fertilizer with corresponding amount (which seemed to be the case).

The UDDT's were installed CREPA.

We didn't really study the reasons why the feces and urine weren't reused to a larger extent. My personal impression though is that several factors contributed, e.g. in some cases long distances to the fields, lack of means of transportation of the heavy cans, not enough cans, not enough/persistent guidance in how to reuse.

At the moment we are unfortunately not doing further work on this topic but we are very eager to do so as soon as we get the opportunity. It would be interesting to do a study of the effects on both farming productivity, health and behaviour from the beginning of a latrine project, so that we would be able to have a baseline from the time before the latrines were installed.

Please don't hesitate to ask if you have any questions, I'll be much quicker to reply this time!

Best regards,
Johan

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